1. Field of the Invention
This invention relates to the art of firefighting equipment.
More particularly, this invention relates to a spray nozzle for attachment to a fire hose.
In a further and more specific aspect, the instant invention concerns a firefighting nozzle capable of discharging a variable solid stream and a variable fog spray, with controls for each type of spray being operable independently of and simultaneously with one another.
2. Description of the Prior Art
Firefighting nozzles can be broadly classified into two basic types. The oldest and simplest type of nozzle, known as the solid stream or straight tip nozzle, consists essentially of a tapered cone secured to the end of a fire hose, with a quarter-turn ball valve or similar device incorporated into the nozzle opening for controlling the flow of water. A more modern type of nozzle, known as an automatic nozzle, incorporates a spring-biased disc into the discharge opening for maintaining a substantially constant pressure in the nozzle. Each of the foregoing nozzles has its own advantages and disadvantages which makes it more suitable for certain applications than for others.
The primary advantage of the solid stream nozzle, for instance, is that it concentrates the water from the fire hose into a high force, high velocity, circular stream which is extremely effective in "punching through" fires and burning debris to extinguish flames. A drawback of this type of nozzle, however, is that a very high reaction force is generated by the flow when the control valve is fully opened, making the nozzle difficult and sometimes unsafe for a fireman to handle. The reaction force can be decreased by partially closing the control valve, but this creates severe turbulence in the nozzle, which causes the quality of the stream to deteriorate, and reduces the reach of the stream.
Still another problem encountered with the solid stream nozzles is that tips of various exit orifice diameter must be attached to the nozzle, depending on the available water pressure, water volume, and the number of firefighters available to handle the hose. The necessity to change tips is inconvenient and can cause dangerous delays in responding to a fire.
As a result of the above drawbacks of solid stream nozzles, the automatic nozzle has become more widely used in the United States. One key advantage of the automatic nozzle is that the constant pressure feature allows for a constant reach of the water stream regardless of pressure oscillations at the source. In addition, the automatic nozzle easily incorporates a feature known as "fog generation", which allows the nozzle to emit a conical spray of evenly distributed water droplets. This is done by forming a number of inwardly and forwardly projecting rods or teeth along the inner circumference of the discharge orifice. These teeth cause the water to variably change direction and to be emitted in all directions of the included solid angle of a cone. The resultant fog is highly desirable, since it spreads over a relative wide area, forming a protective shroud cooling the flames in the immediate vicinity of the firefighter. The advantages of this type of nozzle are somewhat diminished, however, by its inability to produce the same type of highly concentrated, forceful stream which is available in a solid stream nozzle for punching through burning debris.
A third type of nozzle, known as the Navy nozzle, consists of a straight tip nozzle and a fog-generating nozzle, provided one above the other. A diverter valve allows the operator to choose which nozzle to use. Even this arrangement is not entirely satisfactory, however, since only one option is available at a time, and the choice of which type of stream to use in a given situation is not always a clear-cut or easy one.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.